There are numerous types of input devices for computer systems, such as optical disk drivers, mouse, keyboards and the like. Among them keyboards are the most important. With constant advance of technology, the keyboards are increasingly being designed and made thinner, smaller and lighter. Conventional keyboards, such as those disclosed in Taiwan patent Nos. 445471, I220213 and M346861, generally have a keycap, a circuit board triggered by the keycap to generate a command signal, a baseboard located at one side of the circuit board and a driven mechanism with two ends connecting to the keycap and baseboard. The keycap is depressible to move towards the circuit board, and the driven mechanism is moved at the same time towards the circuit board to set on a circuit switch on the circuit board to generate a corresponding command signal. While the aforesaid keyboard structure can achieve the object of command input, the driven mechanism is formed at a certain thickness that becomes a constraint of keyboard and makes thinner keyboard impossible, hence cannot meet the prevailing requirement of lightness, thinness and slimness of the keyboard.
In order to overcome the aforesaid problem, some producers have proposed other keyboard designs, such as Taiwan patent Nos. M434979, M419973 and M426075, which change the form of the driven mechanism or propose other similar structure to replace the conventional driven mechanism. Although they can reduce the thickness of the keyboard to some degree, they still cannot fully meet most consumers' requirement in terms of thin keyboard. There are still rooms for improvement.